fs: dlm: add lkb debugfs functionality

This patch adds functionality to add an lkb during runtime. This is a
highly debugging feature only, wrong input can crash the kernel. It is a
early state feature as well. The goal is to provide a user interface for
manipulate dlm state and combine it with the rawmsg feature. It is
debugfs functionality, we don't care about UAPI breakage. Even it's
possible to add lkb's/rsb's which could never be exists in such wat by
using normal DLM operation. The user of this interface always need to
think before using this feature, not every crash which happens can really
occur during normal dlm operation.

Future there should be more functionality to add a more realistic lkb
which reflects normal DLM state inside the kernel. For now this is
enough.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

1 files changed, 31 insertions, 1 deletions

diff --git a/fs/dlm/debug_fs.c b/fs/dlm/debug_fs.c
index 555904eeea8e..2ead4751d655 100644
--- a/fs/dlm/debug_fs.c
+++ b/fs/dlm/debug_fs.c
@@ -635,6 +635,35 @@ static int table_open2(struct inode *inode, struct file *file)
 	return 0;
 }
 
+static ssize_t table_write2(struct file *file, const char __user *user_buf,
+			    size_t count, loff_t *ppos)
+{
+	struct seq_file *seq = file->private_data;
+	int n, len, lkb_nodeid, lkb_status, error;
+	char name[DLM_RESNAME_MAXLEN] = {};
+	struct dlm_ls *ls = seq->private;
+	unsigned int lkb_flags;
+	char buf[256] = {};
+	uint32_t lkb_id;
+
+	if (copy_from_user(buf, user_buf,
+			   min_t(size_t, sizeof(buf) - 1, count)))
+		return -EFAULT;
+
+	n = sscanf(buf, "%x %" __stringify(DLM_RESNAME_MAXLEN) "s %x %d %d",
+		   &lkb_id, name, &lkb_flags, &lkb_nodeid, &lkb_status);
+	if (n != 5)
+		return -EINVAL;
+
+	len = strnlen(name, DLM_RESNAME_MAXLEN);
+	error = dlm_debug_add_lkb(ls, lkb_id, name, len, lkb_flags,
+				  lkb_nodeid, lkb_status);
+	if (error)
+		return error;
+
+	return count;
+}
+
 static int table_open3(struct inode *inode, struct file *file)
 {
 	struct seq_file *seq;
@@ -675,6 +704,7 @@ static const struct file_operations format2_fops = {
 	.owner   = THIS_MODULE,
 	.open    = table_open2,
 	.read    = seq_read,
+	.write   = table_write2,
 	.llseek  = seq_lseek,
 	.release = seq_release
 };
@@ -846,7 +876,7 @@ void dlm_create_debug_file(struct dlm_ls *ls)
 	snprintf(name, DLM_LOCKSPACE_LEN + 8, "%s_locks", ls->ls_name);
 
 	ls->ls_debug_locks_dentry = debugfs_create_file(name,
-							S_IFREG | S_IRUGO,
+							0644,
 							dlm_root,
 							ls,
 							&format2_fops);